login
Subscripts for "secondary twin-primes": numbers k such that prime(prime(k)+1) - prime(prime(k)) = A073124(k) = 2.
6

%I #18 Aug 13 2024 05:31:48

%S 1,2,3,4,6,7,13,14,23,24,29,30,40,59,63,65,71,74,90,103,106,110,112,

%T 117,122,128,132,187,188,193,207,248,257,258,267,271,281,285,292,296,

%U 299,300,303,304,311,317,325,340,343,344,354,356,360,368,382,389,395,402

%N Subscripts for "secondary twin-primes": numbers k such that prime(prime(k)+1) - prime(prime(k)) = A073124(k) = 2.

%H Ivan Neretin, <a href="/A096477/b096477.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = primepi(A096478(n)). - _Amiram Eldar_, Aug 13 2024

%e 24 is a term since prime(prime(24)+1) - prime(prime(24)) = prime(89+1) - prime(89) = 463 - 461 = 2.

%t Flatten[Position[Table[Prime[Prime[n]+1]-Prime[Prime[n]], {n, 1, 1000}], 2]]

%Y Cf. A006450, A072677, A073124, A096478.

%K nonn

%O 1,2

%A _Labos Elemer_, Jun 23 2004